CARE Baltimore

Systems Analysis of Carpet as a Feed to Cement Kilns: 

Systems Analysis of Carpet as a Feed to Cement Kilns Matthew J. Realff School Of Chemical Engineering Georgia Tech

Regional System Design: 

Regional System Design Design, evaluate and test components of a system to recover post manufacturing and post consumer carpet & textile waste on a regional basis. Should be reproducible, robust and scalable, leverage existing carpet recycling efforts, economically sound.

Recycling Network Overview: 

Recycling Network Overview Nylon 6,6 $0.04/lb Nylon 6 Process Honeywell, Augusta Ga. Kiln $0.06/lb Whitfield County MonoFill $25.50 baled $45.50 unbaled Local Landfill Carpet Manufacturing Commercial & Residential Replacement Fuel + Raw Material Substitution $ Variable

Collection Potential Estimation: 

Collection Potential Estimation Hypothesis 1 1) New Sales will be partially for replacement and therefore new sales volume will be a predictor of carpet available for retirement. US New Sales from US Dept of Commerce Data Replacement Fraction ~ 0.66 Hypothesis 2 – Total available carpet 2) Average carpet life in residential setting is 13 years Carpet scales linearly with population. Carpet Available in Region = Current Population of Region Total US Population x ? US Sales 1988 from US Dept of Commerce Data provide a rough estimate - Data is summarized in CRI Reports

Carpet Sales: 

Carpet Sales Area data from CRI 1999 Carpet & Rug Industry Review Appendix Table 6

Basics of Cement Kiln: 

Feed Materials (Dry Powder or Wet Slurry) Preheater Tower Hot Exit Gases Pre Calciner CaCO3  CaO + CO2 Rotating Kiln Fuel Flame (3400 F) Hot Clinker Product (2700 F) Back End Fuel Basics of Cement Kiln Carpet Feed Hopper Auger Feed of Carpet Drop in Carpet Feed

What is the Potential?: 

What is the Potential? U.S Clinker Production = 7 x106 metric tons Btu/ton Clinker (av) = 5.04x106 btu/ton Btu/ton Clinker (coal only) = 3x106 btu/ton Btu/lb carpet ~ [8759 9000 10529] Total U.S. Disposal lbs/year ~ [4x109 5x109] lbs For all kilns at 8% displacement of coal: 1.86x109 lbs of carpet ~ [37% 47%] of annual disposal For kilns with Preheat/Precalciner at 11% displacement of coal: ~ [30% 37%] of annual disposal

Cement Kiln System: more detail: 

Cement Kiln System: more detail Post Manufacture Post Consumer Truck/other Size Reduce Cement Kiln Conveyor System Kiln System Trip to Blue Circle in Marietta is short but what about other lcoations? How can we cost-effectively size-reduce carpet for feeding ?

System Analysis: 

System Analysis Factors Economics Can a system be designed that delivers carpet into the cement kiln at a cost: -to the kiln lower than the fuel and raw material displaced ? -to the carpet collector lower than his other current alternatives? Life Cycle Comparing the preparation/delivery/emissions of current kiln feeds is carpet a better option ? Not a static one-time decision – revision according to alternatives

Total System Economics: 

Total System Economics Collection Economics Economics of recovering, sorting, baling & storing carpet from various locations: Carpet Retail C&D Sites Transport Economics Economics of moving the carpet to the kiln location: Truck Rail (?) Barge (?) Feed Prep & Feed Economics Economics of size reducing carpet and feed system to kiln

Case Study: Tampa Florida: 

Case Study: Tampa Florida Collection - Tampa/St. Petersburg/Clearwater Population (1990) 2,067,959 Carpet Estimation 39.3 million lbs/year (100% collection 1988 purchases) Carpet Collected Composition (40% N66, 30% N6, 30% Other) 26.7 million lbs/year, 39.5 tons/kiln day Kilns – Brooksville Florida. Distance – 55 miles (www.mapquest.com) Kilns Florida Crushed Stone (1987), Dry-Preheater, 1,763 metric ton cement/day Fuels Coal and Alternative Southdown, Inc (1976/1982), Dry-Preheater, 3,718 metric ton/day, Fuels Coal/Oil

Case Study Continued: 

Case Study Continued Kiln Processing (Takes Carpet for free, Kiln Pays Processing) Process in an 8 hr shift Equipment capable of 3,000-7,000 lbs/hr Cost – 0.5c/lb + capital recovery $500/day Transportation (Collector Pays) Assume a Self Haul, 20 tons/load at a cost 1.00/load/mile Note – regular shipping rates closer to $1.50-2.00/load/mile Kiln Fuel Costs Coal $1.6/mmbtu Carpet 9000 btu/lb

Case Study Continued: 

Case Study Continued Fuel Displaced – is it enough to entice kiln to care about ? Is it enough to Process Economically ?

Case Study Conclusions: 

Case Study Conclusions Detailed analysis required and case specific, economics not clear cut. Economics from collector’s viewpoint currently good (avoided landfill fees vs transportation to kiln) for “short” distances. Volumes are low for investment to justify itself if carpet is the only feed to a de novo system. Large urban centers required Tampa 35th largest metro region 68% of U.S. population in urban centers larger than Tampa Transportation costs need to be kept low Milwaukee, WI  Buffalo Iowa, 227 miles Kilns on Mississippi? (Clarksville, MO)